Differentiation of spring carabid beetle assemblages between semi‐natural habitats and adjoining winter wheat

Abstract

Abstract Semi‐natural habitats are part of agri‐environment programmes throughout Europe. Little is known about activity‐density and assemblage composition of carabid beetles within sown wildflower areas (SWA) compared with conventional grassy field margins and adjoining arable fields. In 10 landscapes, two pairs of winter wheat fields with adjoining SWA and grassy field margin were studied. We compared activity‐density, species richness, ecological traits and assemblage composition of carabids among 20 winter wheat fields, 10 adjoining grassy field margins and 10 adjoining SWA. Beetle activity‐density was higher in wheat fields compared with adjoining semi‐natural habitats regarding total carabids, macropterous, polyphagous‐carnivorous and euryoecious open habitat beetles. Although total species richness (analysis of variance) did not significantly differ among habitat types, we found significantly higher species numbers in SWA than in wheat fields adjoining SWA and grassy margins when the number of recorded species was standardized to the number of individuals (rarefaction). Carabid assemblages in wheat fields differed from assemblages in adjoining SWA and grassy margins. The results of the present study emphasize the important contribution of semi‐natural habitats to diversify the spring carabid fauna in agroecosystems. In particular, SWA were shown to be useful to enhance carabid biodiversity conservation in agroecosystems, rather than to enhance their density‐dependent functions.